The present invention relates to a clutch drum, a method of manufacturing a clutch drum and an apparatus for forming a tooth profile which are used for manufacturing a clutch drum of an automatic transmission.
A clutch drum of an automatic transmission in accordance with a related art is formed in a cup shape and has a peripheral wall having a tooth profile. The clutch drum has a circumferential groove for mounting a snap ring in a portion close to an opening end of an inside (or inwardly) projecting portion on the peripheral wall. In order to manufacture the clutch drum, a tooth profile forming apparatus provided with a punch having an outer peripheral surface formed in a tooth profile and a die having an inner peripheral surface formed in a tooth profile is used. When the punch to which a base material having a cup shape is fitted is combined with the die, a peripheral wall of the base material is molded to a predetermined tooth profile between the outer peripheral surface of the punch and the inner peripheral surface of the die.
As shown in FIG. 1A, the peripheral wall Cw of the base material Cp has a tooth profile portion. A cross sectional shape of the tooth profile portion is not changed from an opening end thereof to a closed side thereof.
In the tooth profile portion of the peripheral wall Cw, a circumferential groove Cd for mounting a snap ring is formed. The circumferential groove Cd is formed by a cutting process. The circumferential groove Cd is formed at a portion close to the open end of the inside projecting portion Cm.